MATERIALS AND METHODS: Rats were subjected to 5 hours of coronary ligation followed by reperfusion, and 10 days after MI, animals were randomized into either the MSCs transplantation (MI-MSC, n=8) group or the control (n=8) group. Allogeneic MSCs (3x10(6) cells) or media were epicardially injected into the center and the border area of the infarct scar.

RESULTS: Four weeks after the MSCs transplantation, the echocardiogram showed preserved anterior regional wall motion and increases in fractional shortening in the MI-MSC heart relative to the control heart. Left ventricular (LV) end diastolic pressure was smaller in the MI-MSC than in the control group. Implanted MSCs formed islands of cell clusters on the border of the infarct scar, and the cells were positively immunostained by sarcomeric alpha-actinin and cardiac troponin T. In addition, the number of microvessels on the border area of the infarct scar was greater in the MI-MSC than in the control group.

CONCLUSION: Allogeneic MSCs transplanted into the MI scar formed clusters of cell grafts on the border of the infarct, expressed cardiac muscle proteins, increased microvessel formation, and improved regional and global LV function. Our data indicate that CCM using MSCs may have a significant role in the treatment of post-MI heart failure.